1. Field of the Invention
The present invention relates to a circuit-component supplying apparatus which supplies circuit components such as electric-circuit or electronic-circuit components, a circuit-component feeder which stores and supplies circuit components, and a circuit-component supplying method, and relates particularly to the art of improving the circuit-component supplying efficiency.
2. Related Art Statement
There is known a circuit-component supplying apparatus which includes a plurality of feeders each of which stores a number of circuit components, and which selects an appropriate one of the feeders so that the selected feeder feeds or supplies the components. More specifically described, the known circuit-component supplying apparatus includes (A) a plurality of feeders each of which stores a plurality of circuit components of a same sort and which supplies the components one by one from a component-supply portion thereof; (B) a movable table which holds the feeders such that the respective component-supply portions of the feeders are arranged along a line and which is movable in a direction parallel to the line; and (C) a table-driving device which moves and stops the movable table to position the component-supply portion of each of the feeders at a predetermined component-supplying position.
The movable table may be a linearly movable table to which a plurality of feeders are attached such that the respective component-supply portions of the feeders are arranged along a straight line and which is movable in a direction parallel to the straight line; or a full-circular table which is rotatable about a vertical axis line and to which a plurality of feeders are attached such that the respective component-supply portions of the feeders are arranged along a circle whose center rides on the axis line.
Each of the feeders includes a main portion and a circuit-component holding portion. For example, U.S. patent application Ser. No. 08/637,380 discloses a circuit-component supplying apparatus which includes a feeder including a main portion and additionally a reel-holding portion as a component-holding portion. In the disclosed apparatus, circuit components are given in the form of a tape, which is wound around a reel which is held by the reel-holding portion such that the reel is rotatable about an axis line thereof and is detachable from the reel-holding portion. The reel-holding portion is fixed to the main portion, and the tape is drawn out of the reel by a tape-feeding device provided in the main portion, so that the components carried on the tape are fed one by one to a component-supply portion of the feeder.
The main portion of each feeder is held by the movable table, so that the main portion is moved with the table as if it were an integral portion of the table. Thus, the main portion does not vibrate relative to the table. On the other hand, the component-holding portion may vibrate relative to the table. If the component-holding portion is sufficiently large, the vibration thereof will sufficiently decrease. However, the mass of each feeder will increase and, when the movable table holding those feeders is accelerated and decelerated, the vibration of the circuit-component supplying apparatus as a whole will increase.
Hence, the circuit-component supplying apparatus disclosed in the above-identified U.S. patent application employs a reel-holding-portion-vibration preventing device. The preventing device includes a bucket which is fixed to the movable table and in which the respective reel-holding portions of the feeders are accommodated, and two engagement members provided on the bucket. Each of the two engagement members has a plurality of engagement recesses each of which is engageable with a corresponding one of two engagement plates of each of the reel-holding portions. In the state in which the two engagement plates of each reel-holding portion are engaged with one of the engagement recesses of one of the two engagement members and a corresponding one of the engagement recesses of the other engagement member, respectively, the reel-holding portion is prevented from vibrating in the direction of width thereof, i.e., in the direction of movement of the movable table. In particular, one of the two engagement members is provided with a pressing device which presses one engagement plate of the reel-holding portion against one side surface of one engagement recess, so as to prevent the movement of the plate. Thus, the reel-holding portion does not need a high rigidity, for the purpose of being prevented from vibrating when the movable table is accelerated and decelerated. Therefore, the prior apparatus is free from the problem of failing to supply circuit components because the component-supply portion of each feeder is moved out of position due to the vibration of the main portion thereof resulting from the vibration of the reel-holding portion thereof.
In the above-mentioned prior apparatus, the total mass of the movable elements including the movable table and the plurality of feeders is less increased than in the case where each of the reel-holding portions has a high rigidity. However, since the prior apparatus employs the reel-holding-portion-vibration preventing device, the total mass of the movable elements is more or less increased. Therefore, if the acceleration and deceleration of the movable table are increased for improving the component supplying efficiency, the vibration of the supplying apparatus as a whole will be large, which leads to lowering the accuracy of positioning of each feeder and even causing each feeder to fail to supply a circuit component or components. In addition, since the total mass is high, the table-driving device should be one which has a large capacity or high performance, which leads to increasing the production cost of the supplying apparatus. On the other hand, if the movable table is moved at low acceleration and deceleration for improving the accuracy of positioning of each feeder and thereby improving the reliability of supplying of circuit components, the component supplying efficiency will be lowered.